Paddle wheel regenerative heat exchanger



J. w. TUMAVICUS PADDLE WHEEL REGENERATIVE HEAT EXCHANGER June 20, 1967 5 Sheets-Sheet l Filed July 28, 1965 QN *Il 1./ .vw mm wm mm Nm @w n m. O O O on: j .vm ./m J m mm 'l l Q @Lv l mwikmwm Nm lf om x Om 0 0 0 @M9 woooo Nw. Olm o* o@ om r/ R a a Nv om N June 20, 1967 J. w. wmAvlcus 3,326,274

PADDLE WHEEL REGENERATIVE HEAT EXCHANGER Filed Ju1y128, 1965 5 SheebS-Sheet 2 INVENTOR. JUL/us l/M 7Z/MAv/cus www A TT ORNE Y' June 20, 1967 J, w. 'ruMAvlcUs 3,326,274

PADDLE WHEEL REGENERATIVE HEAT EXCHANGER Filed July 28, 1965 l 5 Sheets-Sheet Z L gf 108 ed,

loo Ho INVENTOR. JUL/us W. TUMA v/cus mk WL@ BY TTORNE Y6' United States Patent O 3,326,274 PADDLE WHEEL REGENERATIVE HEAT EXCHANGER Julius W. Tumavicus, Oid Saybrook, Conn., assigner to United Aircraft Corporation, East Hartford, Conn., a

corporation of Delaware Filed July 28, 1965, Ser. No. 475,381 9 Claims. (Cl. 165-10) ABSTRACTv OF THE DISCLOSURE A regenerative heat exchanger of the rotary paddle wheel type in which the rotor is toroidal and is divided into segmental compartments by radial partitions, each compartment having a folded heat exchange matrix material therein to dispose a web obliquely of the path of fluid flow and in a manner to minimize distortion stress in said compartment partitions due to temperature differentials.

The invention herein disclosed is directed gener-ally to regenerative type heat exchanger devices, and more particularly to exchangers of the |rotary type wherein there is employed a high heat-capacity porous matrix through which a hot fluid and then a cool fluid are successively passed as the matrix is moved to cause elements or increments thereof to pass successively through separated stations or zones.

A primary purpose of devices of this type is for the utilization and recovery of heat energy remaining in exhaust gases of a gas turbine engine, by transferring7 this residual energy to the incoming air fed to the combustion chamber or chambers of the engine. Generally this is accomplished by rst passing each increment or segment of a high heat-capacity fluid-pervious matrix material through a zone defined by suitable ducts by which hot exhaust gases are constrained to pass through that matrix increment temporarily residing in such zone; and then moving such increment to a second zone, spaced from the rs-t, through which a relatively cool fluid, lfor example air, is similarly ducted so as to pass through the previously heated matrix increment, whereby to extract therefrom the heat energy thus stored in the matrix. This process is made continuous by again returning the matrix increment to the same or a different hot gas ozone, and the cycle is repeated, resulting in a rotary type of regenerating device.

It is necessary for the proper operation of these devices to isolate the zones through which the hot and cool gases are passed so that leakage or 'by-pass does not occur directly from one to the other within lthe heat exchange device itself. Accordingly, the zones are spaced or separated along the path followed by the matrix material, and covers or tunnels are provided to block off or enclose that increment of the matrix which is in transit between successive zones. Still further precaution is needed against leakage of the gases 4around the matrix and along the tunnels from one zone to another, as well as escape completely of the exchanger housing, where the gas pressures are substantially above atmospheric, as is the case in gas turbine engines. Therefore various seals making close lit .between the moving matrix material and the stationary portions of the exchanger housing, including the tunnels, must also be provided. The problems of design encountered here are further complicated by high operating temperatures, and more particularly by high pressure and temperature differentials existing across portions of the exchanger device, whereby the development and construction of a practical, commercial form of exchanger is greatly complicated.

Some of the important considerations to be borne in mind are the desirability of maximum matrix area to develop maximum heat transfer capacity, yet maintenance of hee minimum flow impedance and minimum overall physical size and -weight of the device. Mechanical design must be such that eilicient sealing can be provided by reliable, uncomplicated means, and further that such sealing means have substantial tolerance to physical or structural change due to thermal expansion and contraction. Concomitantly, the design should avoid or reduce as much as possible physical stresses and dimensional changes resulting from unequal or differential heating of various parts Within the device.

In gas turbine engines using a rotary regenerator, the overall dimension of the engine is regularly limited by the necessary diameter of the rota-ry element of the heat exchanger. Obviously in many installations, as in aircraft, -the overall diameter of the engine is desirably kept to a minimum. Accordingly, a feature of the invention is a substantial increase in the effective area of the heat exchanger without and increase in the overall radial dimension.

One form of rotary heat exchanger is shown in the copending application of Turnavicus et al., Ser. No. 190,- 300, filed Apr. 26, 1962 now Patent No. 3,117,928. That heat exchanger has the heat absorbing matrix arranged around a periphery of a torus-shaped rotary element, and the area of the matrix through which the fluids to be heated and cooled must pass is thus limited by the radii of the annulus. One of the features of the present invention, is to provide a substantially larger effective area of matrix material within the same size torus.

Another feature oft he present invention is the arrangement of the material of the heat exchange matrix in a torus in such manner as to minimize pressure drop yet provide an effectively larger matrix area and heat exchange capacity than heretofore obtained in conventional torus type regenerators. To this end the invention comprehends the folding of the matrix material in a particular manner and the arrangement of such folded matrix between radial- -ly extending bulkheads in the annulus, with the web of matrix extending obliquely between adjacent bulkheads.

Another feature is the arrangement of the matrix to minimize leakage past the matrix material and thereby to effect a maximum amount of liuid flow through the matrix, whereby to increase the efficiency of heat transfer by the device.

These and other objects of the invention, as will become apparent from the description which follows, are illustrated with reference to the `accompanying drawings, in which FIG. 1 is a cross sectional view of a typical turbine engine `wherein the novel rotary regenerative type exchanger is incorporated, taken along line 1--1 of FIG. 2;

FIG. 2 is a sectional view of the engine, taken on line 2-2 of FIG. l;

FIG. 3 is a fragmentary view in plan showing portions of the rotor and matrix of the regenerator;

FIG. 4 is a sectional view taken along line 4 4 of FIG. 3; and

FIG. 5 is a fragmentary View in section of a portion of the rotor, taken on line 5 5 of FIG. 3.

Before describing in detail the rotary .regenerator of the invention, a brief general outline of the relation of such regenerator to a typical turbine engine will be made with reference to the illustration in FIG. 1.

Engine 10 comprises a compressor section 12 including an impeller 14 carried by shaft 16 suitably journaled in forward and aft bulkhead members 18, 19, of a housing or frame 20 serving generally to enclose the compressor and combustion sections of the turbine engine. Air entering the annular intake 22 of the engine is compressed by impeller 14 into an annular plenum chamber 24 connected .by suitable transition ducting 26 to an air inlet port 2S n the housing of a rotary regenerating heat exchanger 30, o be described in further detail presently.

The compressed ail passes axially through exchanger ection 30, exciting at air outlet port 32 which opens nto a second plenum chamber 34. Plenum 34, in turn, :ommunicates with a combustion chamber 36 by means of i plurality of ports 38 provided in vannular rear bulkhead I0. An apertured flame tube 42 positioned in the cornaustion chamber is connected by suitable transition ductng to a first-stage or compressor turbine nozzle 44, and 1 turbine 46 is positioned adjacent this nozzle, being secured to the rear end of shaft 16 for driving the compressor impeller 14.

Immediately behind this first-stage turbine 46 there is located a second turbine nozzle 50 and turbine 52. This turbine nozzle is supported in bulkhead 19, while turbine S2 is mounted on shaft 54, the latter being journaled for rotation independently of the compressor shaft 16. Shaft 54 constitutes the power output shaft from which useful torque for motive purposes is obtained from the engine.

The engine is provided With a fuel nozzle and igniter, not shown, in the combustion chamber, and exhaust `gases issuing from the chamber are directed by nozzles 44, 50, past the respective turbines 46, 52, causing them to be rotated. The exhaust gases then exiting from the turbine section are collected in a duct 56 which delivers them to port S8 in the housing of the rotary regenerator section 30. The gases pass axially through the matrix of the regenerator section, emerging at port 60 of housing 30 and are then dumped overboard through suitable ducting 62.

It will 'be noted from the illustration that the compressed air duct 26 incorporates a return bend section 64. This is necessary to effect a desired countercurrent passage of the a-ir and exhaust gases during their respective passes through the regenerator.

The relative positions of the compressed air and exhaust gas ports in regenerator housing 30 is illustrated more particularly in FIG. 2. As shown, inlet air port 28 and the corresponding outlet 32 on the axially opposite side of the regenerator extend arcuately about the regenerator substantially less than one-half of its periphery, while exhaust port 58 and its axially opposite counterpant 60 occupy an arcuate extent of substantially more than onehalf the periphery of the unit. The two sets of ports 28, 32 and 58, 60, respectively, are however symmetrically oriented about the axis of the regenerator. The difference in size of the two sets of ports is of course designed to compensate for the difference in density of the relatively low temperature compressed air and high temperature exhaust gases. The arcuate extent lof .the openings in each of the ports in each of the sets is, in each instance, no greater than the distance between the segments or an integral number of segments into which the regenerator matrix is divided by radial partitions as will be further described. This is a necessary relationship in order to prevent leakage or by-passing of the gases within the regenerator unit, as further appears herein.

Turning now to a detailed consideration of lthe regenerator section 30, this includes a spl-it housing comprising sections 70, 72 which together form a hollow torus which in turn surrounds a cylindrical housing or shroud 74 enclosing the forward section of `the power shaft 54 Y immediately behind turbine 52.

The regeneratoi specifically here illustrated comprises a toroidal rotor 80 of essentially circular cross section which is supported by suitable bearing and seal structure 83 not here shown in detail as not being material to the present invention. Instead of being circular, the rotor may of course assume an egg-shaped, elliptical or other cross section. Bearing structure 83 is carried on the aft end of shroud 74. Reduction gearing (not shown) between shaft 54 and hub 82 of rotor 80 is provided to drive the rotor at `relatively low speed.

Rotor 80 is essentially completely toroidal. Similarly the housing sections 70, 72 form an essentially completely toroidal structure whose contour is interrupted only by the compressed air and exhaust gas ports previously mentioned.

The rotor itself is divided circumferentially into increments by radial partitions which latter are continuous in their periphery to conform closely to the interior cross sectional area of the hollow torus formed by housing members '70, 72. On the radially inner periphery of the torus, partitions 90 are slightly truncated where they are joined to the annular hub 82 for support. Each of the partitions 90 is formed in the circular portion of its periphery with a groove 92 for the reception therein of a sealing ring 94. The groove and ring 92, 94, respectively, extend throughout the circular periphery of partition 90, and the ring is clamped or otherwise secured at its opposite ends in hub 28 on axially opposite sides of the rotor. Each ring 94 makes a sliding t with the inner wall of the annulus, thereby preventing leakage circumferentially around the outer periphery of the rotor between rotor compartments formed by partitions 90.

Between adjacent partitions 90, at the radially outer periphery of the rotor, a plate 96 is disposed in a plane perpendicular to the radius passing through the center of each compartment 100. Plate 96 thus intersects the adjacent partitions 90 along a chord line perpendicular to the axis of symmetry of the partition. Plate 96 is formed along its rear or radially outer face with a central rib 102 of generally segmental form, constituting a fillet between plate 96 and the outer periphery of the rotor. Rib 102 is grooved, as at 104, along its arcuate periphery, and a thrust seal 106 is disposed therein. Seal 106 makes sliding contact with the inner surface of the toroidal housing of the rotor and serves to prevent bypass or leakage axially of the rotor between the upstream and downstream sides thereof. Seals 106 extend the full distance between rings 94 in each rotor compartment or segment 100, but do not interrupt rings 94.

As here shown, each partition 90 is additionally supported in its radial position by a brace or spacing rod 108 secured centrally to partitions 90 by suitable mounting pads or feet 110 by which it is fastened to the partitions.

The heat exchange matrix of the rotor assembly is formed of webs of highly pervious, foraminous heat exchange material having high capacity for absorption of heat. The web is relatively thin, typically consisting of laminations of wire mesh for example, it being desirable to keep to a minimum the pressure drop from uid oW through the matrix. As shown in the accompanying drawings, each compartment 100 of the rotor contains a length or strip of this matrix web. This web strip is secured at its opposite ends, circumferentially of the rotor, to adjacent partitions 90 forming the respective compartment 100. As here shown, and in the preferred embodiment, the circumferentially opposite ends 122 of strip 120 are both fastened, as by Welding or in other suitable manner, to the respective partitions 90 on the same axial side of the rotor, as shown in FIG. 4. Web 120 is of substantially greater length than the circumferential distance between adjacent partitions 90, andthe intermediate portion of the web is accordingly folded in generally radially disposed planes wit-hin compartment 100 toward the axially opposite side of the rotor from that at which the ends 122 are secured. Preferably the web is folded in the form of a V in which the apex of the V is thus disposed closely adjacent the axially opposite side of the rotor from that of which the ends of the web are secured. Suitable provision is made in the intermediate portion of web 120 to allow support rod 10S to pass through, and the web configuration may be further reinforced and strengthened by securing the web to rod 108 where it passes through.

At the radially inward and outward peripheries of each compartment 100, the respective edges of webs 120 are secured to the hub 82 and chord plate 96 of the rotor. Thus, within each compartment 100, the matrix web 120 forms a generally V-shaped trough closed at its opposite ends. As the rotor is turned about its axis, the compressed air or exhaust gases, as the case may be, are thus confined to pass axially through compartment 100, and the matrix web 120 therein. The direction of flow of the two iiuids, i.e. compressed air and exhaust gases, is reversed as previously described in order to effect countercurrent heat exchange operation.

As seen from FIG. 4, the preferred V-shaped configuration of web section 120 within each compartment 100 produces a structure which minimizes differential temperature conditions on the opposite faces of each partition 90. That is, depending upon the direction of axial flow of the fluid through the respective compartment 100, the opposite faces of each partition 90 are always exposed to fluid of the same temperature and pressure. Thus the folding of the web material in generally radially disposed planes within each compartment as above described serves not only to increase the area of matrix webbing disposed in each compartment, but t-o reduce distortional distresses that would otherwise result from expansion and contraction from temperature differentials existing in partitions 90.

What is claimed is:

1. A regenerative heat exchanger of the rotary type comprising a casing consisting of an annulus having at least two sets of fluid passages therethrough, and means in said casing to separate said sets circumferentially against fluid flow from one set to the other itnernally of said casing, and a rotor in the shape of a torus mounted for rotation in said casing, said torus being divided circumferentially by a plurality of radially directed partitions into segments or compartments, each of said compartments having a web of heat absorptive material therein, said web extending between and being secured at respectively opposite ends circumferentially of the rotor to adjacent partitions at the same axial side of said torus and being folded in its intermediate portions to extend toward the other axial side of said torus in radially disposed planes.

2. A regenerative heat exchanger as defined in claim 1, wherein the fold is symmetrical circumferentially of the torus.

3. A regenerative heat exchanger as defined in claim 1, wherein the fold is in the shape of a V.

4. A rotary heat exchanging regenerator as defined in claim 1, wherein each of said Webs is positioned at an acute angle to the main axis of the torus and at an acute angle to the normal direction of flow of fiuid into and out of the torus. v

5. A toroidal regenerator as defined in claim 1, wherein the webs rbetween adjacent partitions are arranged in V- shape, with both legs of the V at an acute angle to the axis of the torus.

6. A toroidal regenerator as defined in claim 1, wherein the partitions are substantially in axial planes.

7. A toroidal regenerator as defined in claim 1, wherein the partitions are substantially circular and in axial planes.

8. A toroidal heat exchanging rotary regenerator including a base, a t-orus mounted for rotation about its main axis on said base, and means for directing fluid fiow axially through said torus, said torus having circumferentially spaced bulkheads therein dividing it into a plurality of generally segmental compantments, a plate connecting adjacent bulkheads adjacent the outer periphery of the torus, said plate extending substantially parallel to the axis of the torus and perpendicular to the radius passing through the center of the compartment, and webs of relatively thin flat matrix material disposed between the bulk-heads in each of said compartments in generally radially directed planes.

9. A toroidal regenerator as defined in claim 8, wherein said Webs of matrix material are secured along respective edges to the bulkheads and connecting plate to direct substantially all of the fluid flow through the matrix.

References Cited UNITED STATES PATENTS 2,503,651 4/1950 Alcock 165-8 2,586,250 2/1952 Parker 165-10 X 2,757,907 8/ 1956 Williams 165-9 2,896,920 7/ 1959 Weller 165-9 2,902,267 9/1959 Rich 16S-9 3,177,928 5/ 1965 Tumavicus et al 165--7 ROBERT A. OLEARY, Primary Examiner.

T. W. STREULE, Assistant Examiner. 

1. A REGENERATIVE HEAT EXCHANGER OF THE ROTARY TYPE COMPRISING A CASING CONSISTING OF AN ANNULUS HAVING AT LEAST TWO SETS OF FLUID PASSAGES THERETHROUGH, AND MEANS IN SAID CASING TO SEPARATE SAID SETS CIRCUMFERENTIALLY AGAINST FLUID FLOW FROM ONE SET TO THE OTHER INTERNALLY OF SAID CASING, AND A ROTOR IN THE SHAPE OF A TORUS MOUNTED FOR ROTATION IN SAID CASING, SAID TORUS BEING DIVIDED CIRCUMFERENTIALLY BY A PLURALITY OF RADIALLY DIRECTED PARTITIONS INTO SEGMENTS OR COMPARTMENTS, EACH OF SAID COMPARTMENTS HAVING A WEB OF HEAT ABSORPTIVE MATERIAL THEREIN, SAID WEB EXTENDING BETWEEN AND BEING SECURED AT RESPECTIVELY OPPOSITE ENDS CIRCUMFERENTIALLY OF THE ROTOR TO ADJACENT PARTITIONS AT THE SAME AXIAL SIDE OF SAID TORUS AND BEING FOLDED IN ITS INTERMEDIATE PORTIONS TO EXTEND TOWARD THE OTHER AXIAL SIDE OF SAID TORUS IN RADIALLY DISPOSED PLANES. 